1. Field of the Invention
This invention relates to novel compositions comprising a linear low density copolymer of ethylene and a minor amount of an olefin containing 4 to 10 carbon atoms (LLDPE), and to films of improved properties formed from such compositions. Also included in the invention is the process of forming blown films from such compositions which is accomplished with improved processability.
2. Description of Related Art
The following information is disclosed in accordance with the terms of 37 CFR 1.56, 1.97 and 1.98.
U.S. Pat. No. 4,565,847, issued Jan. 21, 1986 to S. K. Bahl et al., discloses blends of LLDPE, polypropylene (PP) or ethylene-propoylene copolymer, and ethylene-propylene-diene monomer rubber (EPDM), which are stated to form films having improved MD tear strength and dart drop impact properties.
U.S. Pat. No. 4,579,912, issued Apr. 1, 1986 to P. J. Canterino et al., teaches blends of LLDPE and an aromatic polymer, e.g., polystyrene, which are stated to form films of improved MD tear strength and higher stiffness compared to LLDPE alone.
U.S. Pat. No. 4,657,982, issued Apr. 14, 1986 to A. K. Breck et al., discloses film-forming blends of a linear copolymer of ethylene and a C.sub.4 to C.sub.8 alpha-olefin, and two "polybutenes," one having a number average molecular weight of 500 to 1500 and the other a number average molecular weight of 1700 to 10,000.
U.S. Pat. No. 4,456,660, issued June 26, 1984 to E. A. Columbo, teaches blends of conventional branched low density polyethylene (LDPE) and polybutene-1 used to prepare laminated films with unblended LPDE which are stated to be tough and to have good tear resistance.
U.S. Pat. No. 3,660,530 issued May 2, 1972 to Hoblit et al., discloses blends of high density polyethylene and block copolymers of polyethylene and a polymer of butene-1 which are stated to have improved stress crack resistance.
U.S. Pat. No. 4,430,476, issued Feb. 7, 1984 to Liu, discloses the improvement of the impact resistance and ductility of notched polycarbonate resin articles by blending the polycarbonate with varying amounts of an alkenyl aromatic copolymer, e.g., an ABS resin, and an LLDPE.
Romanian Patent No. 63,726 of Petraru et al., published June 30, 1978 [abstracted in C.A. 91(24)194203r] discloses blends of 100 parts of low density polyethylene, 2 to 20 parts of the ABS copolymer, and 10 to 15 parts of carbon black extruded into films with transverse and longitudinal tensile strengths of 160 and 151 kg/cm.sup.2, tear strength of 86 and 84 kg/cm.sup.2, and breaking elongations of 640 and 660% respectively.
Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Vol. 1., Wiley-Interscience, 1981, pages 442 to 445, and Hawley, Condensed Chemical Dictionary, Tenth Edition, Van Nostrand Reinhold, 1981, page 3, describe typical ABS resins contemplated under this invention.
Pending parent application Ser. No. 266,957, filed Nov. 3, 1988 discloses and claims blends of LLDPE and a minor amount of a butene-1 polymer which can be formed into films having improved impact properties.
Pending parent application Serial No. 295,430, filed Jan. 10, 1989 discloses and claims blends of LLDPE and a minor amount of an ABS resin which can be formed into films having improved antiblocking, impact and MD tear resistance properties.